Pivoted valve plate for a pump assembly



Nov. 19, 1957 l.. L. AsPELlN 2,813,493

PIVOTED VALVE lPLATE FOR A PUMP*ASSEMBLYy Filed Nov. 25, 1955 2 Sheets-Sheet L LESLIE sPEL/N Nov. 19, 1957 w. H. HAGEDORN 2,313,428

ROTARY LAWN MOWER BLADE BALANCER 2 Sheets--Sheefl 2 Filed Feb. e. 195e' HR. m,

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2,813,493 Patented Nov. 19, 1957 2,813,493 y Plvornn VALVE PLATE FoR A PUMP ASSEMBLY Leslie L. Aspelin, Cleveland Heights, Ohio,. assignor to Thompson Products, Inc., Cleveland, h10, a corporation of Ohio Application November 25, 1955, Serial No. 549,027

8 Claims. (Cl. 103-162) This invention relates generally to hydraulic pumps of the angular piston and rotary cylinder block type and more particularly to means for automatically providing eliicient hydraulic seals at the inlet and outlet ends of such a pump while concurrently reducing the necessity of providing extremely close machining tolerances in the construction of the component pump parts, and taking the form of a self aligning pivoted valve plate supported for pivotal movement in line with the centroid of hydraulic forces acting on the valve plate.

In the production of` high pressure hydraulic pumps of the angular piston and rotary cylinder block type, it is necessary to maintain nearly perfect machining toler-ances and alignment between the pump housing, cylinder blocks, and end or valve plate if high pump etiiciencies and output are to be realized. Small amounts of misalignment between these parts result in leakage from the high pressure side to the low pressure side of the pump with a corresponding loss in pump eiciency and output.

In addition, the requirement of extreme accuracy of alignment in production tolerances results in a greatly increased unit cost of each pump.

According to the present invention, a pivoted valve plate is mounted to pivotally rock in line with the centroid of hydraulic forces acting on the valve plate whereby the valve or end plate at all times remains free to assume a proper position for maintaining a hydraulic seal between the cylinder block and pump housing.

A seal member made of an elastic material is employed for maintaining an hydraulic seal between the valve plate, cylinder blocks, and pump housing, thereby compensating against small misalignments through deformation of the seal member.

An object of the present invention is to provide an angular piston and rotary cylinder block type pump which overcomes the deficiencies of the prior art.

It is an object of the present invention, therefore, to provide an improved valving arrangement for a pump of the type including angular pistons and rotary cylinder blocks.

Another object is to provide an angular pistonand rotary cylinder block type pump in which the necessity of providing closed tolerances is minimized, thereby to provide a pump structure made of simplified, economically produced components, which are convenient to assemble, and rugged in use.

Yet another object of the present invention is to provide an improved sealing arrangement for the valving apparatus of an angular piston and rotary cylinder block type pump.

Other and further objects of this invention will be apparent to those skilled in the art in the following detailed description and the annexed sheets of drawings which illustrate a pump apparatus incorporating the principles of the present invention.

On the drawings: v

Figure l is a longitudinal cross sectional view, with parts in elevation, of a typical angular piston and rotary cylinder block pump embodying the principles of the present invention. The parts of the pump on the right hand side of Fig. 1 are angularly displaced by 90, thereby illustrating additional details of the present invention.

Figure 2 is a fragmentary cross-sectional view similar to the right hand side of Figure l, with parts in elevation, of an alternative embodiment of the present invention.

Figure 3 is an end view of the staggered section of Figures l and 2 taken generally along the lines III-III of Figure 1.

As shown on the drawings:

The pump of the present invention is indicated generally by the reference numeral 10 and comprises a housing 11 having an inlet 12 and outlet 13.

The housing 11 has a cover member 14 fastened to the main body of the housing 11 by a plurality of fasteners 16. The end of the cover member 14 is formed to facilitate connection of the inlet 12 and outlet 13 with suitable conduit connections.

The opposite end of the housing 11 includes a closure member 13 held in lirm assembly with the main body of the housing 11 by a plurality of fasteners 19. A tiange 20 having a plurality of openings 21 is also formed at the end of the housing 11 to facilitate attachment of the pump l@ in a mounting assembly.

A bore extends through the housing 11 and includes a iirst bore 22 and a second bore 23, each. of which is generally cylindrical in configuration. The axes of the cylindrical bores 22 and 23 are angularly inclined with respect to one another and in intersecting relation so that there is formed in the interior of the housing 11 a plane of intersection between the bores 22 and 23 indicated by the reference numeral 24.

Within the bore 22 is provided a cylinder block 26 which is also cylindrical in configuration, being complementary in size and shape with respect to the bore 22 and journaled for rotation therein. The axis of the cylinder block 26 is coincident with the axis of the bore 2.2.

Radially outwardly of this axis of the cylinder block 26 and circumferentially spaced with respect to one another are a plurality of axially extending cylinders or pumping chambers indicated at 27 formed. by through openings extending through the cylinder block 26.

inwardly of the pumping chambers 26 and coincident of the axis of the cylinder block 26 is an enlarged opening 28 in which is received a shaft member 29 having a splined connecting portion 30 extending outwardly of the pump housing 11 for connection to a driving means. The shaft 29 is connected in driving assembly with the cylinder block 26 as at 31 and is provided with additional journaling support by a bearing and seal assembly surrounding the shaft 29 at the locale of the closure member 18.

The bore 22 is closed by an end plate 25 having a pivot boss 32 located opposite the centroid of pressure forces acting on the face of the end plate 25 exposed to `the unevenly distributed pump generated forces in the bore 22. A pivot recess 32a is formed in the closure member 18 offset towards the discharge side of the pump to seat the pivot boss 32.

In the bore 23, there is provided a cylinder block 33 which is generally cylindrical in configuration being complementary in size and shape to the bore 23 and having its rotational axis coincident with the axis of the bore 23.

The cylinder block 33 is also provided with a corresponding plurality of pumping chambers 34 similar in size and location to the pumping chambers 27 in the cylinder block 26. A centrally disposed recess 36 is formed in the cylinder block 33 and bottoms a coil spring 37. One end of the coil spring 37 engages a loading pin 38 reciprocably slidable in the recess 36. The loading pin 38 reciprocates on the axis of the cylinder block 33 and has `an action surface 39 which engages an adjoining action surface 40 formed on a pin portion 41 integral with the cylinder block 26, which is also located on the corresponding axis of the cylinder block 26. Thus the con- -tinuous biasing force exerted by the `coil spring 37 acts between the cylinder blocks 26 and 33 tending to retain the cylinder blocks in separated relation and loaded `against the corresponding cover member 14 and closure member lil.

An angular piston or sleeve 42 is provided for each respective pair of pumping chambers 27 and 34 in the cylinder blocks 26 and 33, and has angularly inclined arm portions such as an arm portion 42a received in a pumping chamber 27 of the cylinder block Z6, and an arm portion @2b received in a pumping chamber 34 of the cylinder block 33. The angularly inclined arms, or arm portions 42a and 42h, are journaled in the corresponding bores or pumping chambers 26 and 33, since the pistons i2 and pumping chambers 27 and 34 are complementary in size and shape to facilitate relative rotation and reciprocation between the parts. Each of the pistons 42 is hol- 'low and has an opening at 43 extending therethrough to simultaneously communicate the pumping chambers 2.7 and 34 with the inlet l2 and outlet i3.

Referring now to Figure 2 in conjunction with Figure l, it will be noted that the coil spring 37 urges the cylinder block 33 into sealing engagement with a valve or end plate 44 formed as a separate member inside of the cover member i4. On one side of the plate 44 there is formed a sealing surface 46 engaging an adjoining end surface 45 formed on the cylinder block 33.

The valve or end plate ifi contains a kidney-shaped inlet slot 47' and a kidney-shaped outlet slot 48 (Fig. 2), which are Ldiarnetrically spaced in relation to each other. A corresponding pair of hollow kidney-shaped axially projecting bosses 49 and Sil, are formed on the cover member ldand extend through the corresponding kidneyshaped slots t7 and i3 in the valve plate 4d. An arcuately shaped inlet port 5l and outlet 52 extends through the bosses 49 and Stl, respectively, thereby communicating the inlet l2 and its outlet t3 with inlet and outlet zones adjacent the end surface 45 of the rotor 33. A sufficient clearance is provided between the kidney-shaped projecting members 49 and 50 of the cover member 14 to permit a small amount of relative movement therebetween.

A raised hemispherical projection or boss 53 on the -valve plate d4 not only maintains a small amount of clearance between the valve plate 44 and cover member 14, but provides a pivot point or fulcrurn about which the valve plate d4 may wobble. The hemispherical pivot point 53 is seated in a complementary bearing recess 54 in the cover member ll4.

The pump operates by its alternate suction and propulsion resulting when its pistons 42 reciprocate in the cylinders 27 and 3d, its suction stroke occurring when the pistons move in register with the inlet port and the propulsion stroke occurring when in register with the outlet port.

lt will be understood therefore, that the pressures acting on the surface 46 of the plate 4d vary from a miniaum at the inlet port 5l to a maximum at the outlet port 52. Consequently the forces tending to push the plate 44 away from the rotor 33 and acting on the surface 46 are unevenly distributed tending to offset the centroid of the forces away from the axis of the rotor 33 towards the disj charge side of the pump.

According to the present invention the pivot point projecting boss 53 is offset towards the discharge side of the pump and preferably at a point opposite the centroid of the resultant hydraulic force acting on the valve plate 44, thereby eliminating any tendency of the valve plate to wobble due to hydraulic forces or loads developed during the pumping cycle.

By virute of such arrangement the valve plate 44 is free to align itself with the abutting end face 45 of the cylinder block 33 along the sealing surface 46 to accommodate any machining inaccuracies in facing-off the engaging surface 45 of the cylinder block 33, which would otherwise result in leakage across the sealing surface 46.

Moreover, the offset recess :54- and the boss 53 from detent means to prevent relative rotation of the valve plate 4d in the pump.

O-ring seal members 56 and 57 are provided yto prevent any leakage between the kidney-shaped slots 47 and 43 and the hollow kidney `shaped rprojecting members 49 and 5d, and are retained in position by suitable grooves in the internal surface of the slots 47 and 48 of the valve plate 44. Alternatively, the seal retaining grooves may be formed on the outer surface of the kidney-shaped projecting members 43 and 5t).

Referring now to Figtue 3, an alternative 4form of the sealing arrangement is illustrated. In this embodiment, the disk-shaped valve plate Val4a is positioned between the cylinder block 33 and ycover member 14a to provide a sealing surface at 46a. A projection 53a between the valve plate alla and cover member 14a provides a pivot point at the centroid of resultant hydraulic force acting on the valve plate 44a and suicient clearance to permit a small amount of wobble between the valve plate and the cover. A complementary recess 54a in the cover member ida provides a bearing surface for the pivot point projection 53a and also serves to prevent any rotational tendencies of the valve plate.

As in the embodiment shown in Figure 1, the valve plate ida will be self-aligning with the cylinder block 33 during the pumping cycle so as to maintain a hydraulic seal along the surface 4de, even though machining inaccuracies of the cylinder block 33 at the sealing surface den would otherwise result in leakage.

A pair of kidney shaped slots 47a and 43a in the valve plate 4a are provided at the inlet and outlet sides of the pump, respectively, and are in registry with a similarly shaped pair of yslots 53 and S9 in the cover member las to thereby define the inlet port Sl and outlet port 52.

To prevent any leakage between the valve plate 44a and cover member 14a, Q-ring seal members are provided, and are retained in position by suitable grooves in the face of the cover member lla around the kidney shaped slots 53 and 59. Alternatively, the seal member retaining grooves may be formed in the face of the valve plate 44a adjacent the cover member Ma around the kidney-shaped inlet and outlet slots 47a and 48a respectively.

in operation, rotation of the shaft 29 will coincidently induce rotation in the cylinder block 26. The pistons 42 will effect a driving connection between the cylinder blocks 26 and so that both cylinder blocks will rotate in unison. Due to the inclination of the arm portions 42a and 42h, the pistons i2 will reciprocate in the pumping chambers 2.7 and 34 to alternately produce a suction and propulsion in each respective bore, when the mouth of the bore comes into registry with the inlet and outlet ports of the cover member ld.

Under normal operatinfy conditions, there is some leakage along the walls of the pumping chambers 27 and 34.

As pump speed and pressure increase, the cylinder block 33 will continue to be urged into closer sealing relationship with the pivoted valve or end plate 44. Thus it will be seen that the necessity for extremely accurate indexing of the cylinder block 33, valve plate 44, mounting flanges on the housing 11, and closure member 14 is substantially reduced according to the teachings of the present invention.

`Although various minor modifications might be suggested by those versed in the art, it should be understood that I wish to embody within the scope of the patent warranted hereon, all such modifications as reasonably and properly come within the scope of my contribution to the art.

I claim as my invention:

1. In a sleeve type pump comprising a housing, a rotatable cylinder block journaled in said housing and having an end face and being rotatable in register with arcuately shaped circumferentially spaced apart inlet and outlet Zones and a cover for said housing subjected to pump generated unevenly distributed forces varying from a minimum at said inlet zone to a maximum at said outlet zone, a valve plate having a sealing surface for engaging said end face and being intersected by inlet and outlet ports formed in said valve plate, and means on said cover forming a pivot fulcrum for said valve plate oiset towards the outlet side of the pump at the centroid of said unevenly distributed forces, thereby to provide a self aligning seal for said end face.

2. In a sleeve type pump comprising a housing, a rotatable cylinder block having a sealing end face journaled in said housing, said cylinder block being rotatable in register with said circumferentially spaced inlet and outlet zones and being subjected to unevenly distributed pump generated forces varying from a minimum at said inlet zone to a maximum at said outlet Zone, a valve plate having a sealing surface for engaging said end face on said cylinder block and being intersected by inlet and outlet ports formed therein, a cover for said pump housing having an inlet and an outlet formed therein registering respectively with said inlet and said outlet ports in said valve plate, and means forming a pivot fulcrum between said valve plate and said cover member offset towards the outlet side of the pump and at the centroid of said unevenly distributed forces to pivotally support said valve plate for self-aligning sealing of said end face, and flexible seal means between said cover member and said valve plate around said ports yieldable upon relative movement of said valve plate and accommodating variations in manufacturing tolerances therebetween.

3. In a sleeve type pump as defined in claim 2, said cover member including axially projecting bosses corresponding in size and shape to said inlet and said outlet ports of said valve plate and being received therein, said exible seal means being disposed around said bosses and in engagement with said valve plate'.

4. In a sleeve type pump as defined in claim 2, said cover member having a back face spaced from but confronting an adjoining wall of said cover member, and said llexible seal means being disposed in sealing engagement between said back face and said adjoining Wall.

5. In a hydraulic pump of the angular piston and rotary cylinder block type, and including a housing, a pair of rotatable cylinder blocks in said housing, a plurality of bores in said cylinder blocks receiving slidable, angled pistons, 'and a cover member closing one end of said housing, the improvement of a pivotally mounted valve plate disposed between the cover member and one of the cylinder blocks, said cover member and valve plate including ball and socket pivot means positioned opposite the centroid of pump generated force acting on the valve plate, thereby providing a self-aligning valve plate to form a hydraulic seal between the cylinder block assembly and the cover member.

6. In a positive displacement pump of the angular piston and rotary cylinder block type, or the like, including a housing having an inlet and an outlet, a pair of rotatable cylinder blocks in said housing having end face sealing surfaces formed thereon, a plurality of bores in said cylinder blocks receiving slidable, angled pistons, and a cover member closing one end of said housing, the improvement of a disk-shaped valve plate engageable with the end face of at least one of said -cylinder blocks and subject to unevenly `distributed pump generated forces varying from a minimum at the inlet to a maximum at the outlet, said valve plate being cooperatively disposed between the cover member and at least one of said cylinder blocks and having arcuate inlet and discharge ports formed therein, said cover member including axially projecting bosses corresponding in size and shape to the inlet and outlet ports of said valve plate, liexible seal means between the valve plate and around the bosses of the cover member, said valve plate including pivot means positioned at the centroid of said pump generated forces to provide a self aligning action and hydraulic seal between the cover member and the valve plate.

7. In a hydraulic pump of the angular piston and rotary cylinder block type, or the like, including a housing having an inlet and outlet, a pair of rotatable cylinder blocks in said housing having end face sealing surfaces formed thereon, a plurality of bores in said cylinder blocks receiving slidable, `angled pistons, and a cover member closing one end of said housing, the improvement of a valve plate engageable with the end face of at least one of said cylinder blocks and subject to unevenly distributed pump generated forces varying from a minimum at the inlet to a maximum at the outlet, said valve plate being disposed between the cover member and one of the cylinder blocks and having arcuate inlet and discharge ports formed therein, said cover member including a pair of recesses in its abutting face adjacent the valve plate circumscribing the inlet and discharge ports, elastic seal means in said recesses, and a pivot support for said valve plate between said cover member and said cylinder block, positioned at the centroid of said pump generated forces to provide a self aligning valve plate and insure Ia hydraulic seal between the cylinder block assembly and cover member.

8. In a pump of the type having a block with bores extending to an end thereof, pistons slidable in the said bores to pump iluid, a housing having a wall spaced from said end of the block, a plate between the end of the block and said housing wall effective to seal the bores against leakage therebetween, and a cooperating pivot and pivot support on said plate and wall respectively to tiltably support the plate and accommodate machining inaccuracies in the block and wall for maintaining said seal.

References Cited in the le of this patent UNITED STATES PATENTS 

